"There is no blame on those who have imaan (alladheena aamanu) and do good works for what they eat, if they have taqwa and imaan and do good works, then have taqwa and imaan, then have taqwa and ihsaan; and Allah loves the people of ihsaan." (Qur'an 5:93)
This is perhaps the most curious verse I have come across. And it's hard to translate because in arabic the words for imaan, ihsaan, and taqwa are used in verb form, which you cant really do in English, so I had to settle with "having imaan", "having ihsaan", "the people of ihsaan", etc.
Anyway, here's what the teacher (ustaadh) Ahmad ibn Idris says,
"[Allah] repeated the word ittaqoo (verb form of having taqwa) three times,and aamanu three times, and said at the end: wa ahsanu (verb form of having ihsan) once. In other words, those who have imaan and do good works are not blamed for what they eat of tayyib (wholesome, pure, nutritious, safe) food, then whenever they eat, it will increase them in imaan and taqwa. And if the eating of tayyib food is with the intention of strengthening the body for obedience, it will increase you in imaan and taqwa. This [was revealed] because some of the companions [of the Prophet] forbade the eating of animal fats [for themselves] while others forbade marriage so that they could give all their time for worship. Then He, exalted be He, said: "then they have taqwa and ihsaan", so ihsaan is equal to having taqwa and imaan together. [Then he quotes the hadith of Gibreel on islaam, imaan, ihsaan]. So if ihsaan is equated to having taqwa and imaan, then he becomes a wali for God has loved him, and if God has loved him, He has become the hearing with which he hears, the seeing with which he sees, and the tongue with which he speaks, as befits His Majesty, glorified and exalted be He. ...."
In other words, while some people might think eating meats or fats is not good for spiritual purposes, if one eats with the intention of getting stronger so that one can be better at obedience to Allah (and obedeince takes many forms such as worship and work, helping others, jihad, and many things that require energy), then this will in fact increase their level of imaan and taqwa and bring them closer to becoming awliya! As the Messenger of Allah, peace be upon him, said: "The strong believer is better and more beloved to Allah than the weak believer, while there is good in both. Cherich and guard those things that benefit you, trust in Allah and seek His help."
Of course eating very little food and cutting out meats or fats can be helpful in specific times, but is not necessary at all times. For example, Ahmad ibn Idris has this to say on preparing to enter the khalwa, after outlining a certain procedure that some shaykhs have recommended for the novice as a way of reducing his food intake:
In any case, he may follow this procedure or he may simply reduce his food as much as he can. What is desirable is moderation in reducing one's food, in accordance with the words of the Prophet, God bless him and grant him peace, "The best of things are those in the middle". And decreasing the amount one drinks is more certain than decreasing one's food. Some have said, "Eat whatever you wish, but do not drink." And the secret of that is that to leave drinking will cause a decrease in food. This is why Abu Yazid al-Bistami said to his nafs one night when it felt too lazy to do his wird: "By God I will not give you water for a year [if you do not do the wird], which will cause you to eat less, and you will have less energy for worship."
[The preperation period before entering the khalwa] also requires avoiding the meat of all animals, whether land or sea animals, and anything that comes from them such as milk and fat, for these foods induce the carnal lusts for those who are young or those who are still strong among the elderly. Except honey, which is not avoided, for eating it cures the spiritual diseases if it is eaten with that intention, and gives one gnosis and lights, by the traces of revelation in it, as God says, "Your Lord gave revelation to the bees" (16:68).... until "Therein is a remedy for men" (16:69). Indeed the sweetness of the divine address became infiltrated into bees and has remained in their progeny who inherit it from generation to generation. They eat bitter things that become sweet in their stomach, as one observes. Thus therein is a remedy for men both physically and spiritually because its fundament is the divine address which is the Qur'an, the word of God. And the Qur'an is a remedy for what is in man's breast, and right guidance and mercy for the believers.
Some of them do not avoid these foods until they begin the spiritual retreat... but [doing that in advance as preparation] is more perfect.
The eating of honey for its spiritual benefits was also recommended by al-Dabbagh, Samman, and Ibn Arabi. Remember that the proper intention while eating honey (curing spiritual ailments) and food in general (increasing in strength for obedience), is key.
1. Ahmad Ibn Idris wrote his treatise on the khalwa more than once, whenever a disciple asked for it, and it differed each time with additions or subtractions in the words or explanations. Here I have combined parts of two different version of the treatise to give a more complete version. One version that I used was translated into English in "Two Sufi Treatises of Ahmad ibn Idris" by Bernde Ratdke, R. Sean O'Fahey, and John O'Kane. Oriens, vol 35, (1996), pg 143-178.
2. Ratdke et al.